Ádám Sándor: For a larger company that might make sense, but there is a pretty big cost involved because the whole management of the cloud itself varies. For example, there might be differences in the API or the UI.
If you're on Google Cloud and you're running your applications on Google Kubernetes Engine, just managing the stuff that is not inside Kubernetes is not rocket science because the APIs and everything are pretty nice, but you will have plenty of code, terraform, or whatever was written that is dealing with that part. It's not that easy to just import part of your application over to Azure or AWS and write some CloudFormation and deal with the pricing and the whatnot. You have to be sufficiently big to be able to utilize these kinds of synergies, as long as you understand that it's not going to be easy to just use multiple providers.